The present invention relates to a passive shield system for injection devices, including syringes, which prevents inadvertent or premature actuation of the shield during normal bulk transportation, handling and processing and permits the user, such as a healthcare worker or patient, to select the timing of the actuation of the shield while assuring shielding of the needle or cannula without additional manual manipulation.
Injection devices including syringes are well known medical devices for administering medicaments, drugs and vaccines to patients. As used herein, the term xe2x80x9csyringexe2x80x9d is intended to cover the various types of injection and medical delivery devices. They are also used for other well known purposes in the medical field. Prefilled syringes, for example, are generally considered as those which are filled with a selected dosage of medicament, drug or vaccine by a pharmaceutical manufacturer for distribution to the end user. They are generally comprised of a tubular barrel, which contains the medicament, drug or vaccine and a stopper is slidably received in the barrel. The distal end of the barrel typically includes a needle cannula affixed thereto or a connector for a hypodermic needle, such as a Luer fitting. The open proximal end of the syringe barrel generally includes an integral radial flange and a stopper is inserted by the pharmaceutical manufacturer following loading of the barrel with a suitable medicament, drug or vaccine. The plunger of a prefilled syringe generally includes a stopper, which is moveable in the syringe barrel, a plunger rod, which extends through the open proximal end of the barrel with a thumb pad is typically integrally formed on the proximal end of the rod. The syringe barrel is typically formed of glass, but may be formed of any suitable material including plastic and metal. The plunger and stopper assembly allows the user to apply manual force to the plunger, driving the stopper through the barrel and causing the medicament, drug or vaccine to be delivered through the needle cannula to the patient during an injection.
The use of any sharp-pointed piercing element entails the risk of an accidental needle stick. To avoid accidental needle sticks, the prior art has proposed various types of safety shields for syringes including prefilled syringes as described above. Such safety shields typically include a tubular shield or needle cover which is located in a retracted position for injection and an extended position following injection enclosing at least the end point of the needle cannula of the syringe and preventing accidental needle sticks. The tubular shield or needle cover of the syringe shield systems proposed by the prior art are typically mounted on a body having a cavity for receipt of a syringe and the syringe is inserted into the body by the pharmaceutical company after filling the syringe with a suitable medicament, drug or vaccine. Alternatively, the shield may be mounted directly on the barrel of the syringe.
There are generally three types of safety shield systems for syringes proposed by the prior art. The first type may be characterized as manual shield systems. That is, the shield or needle cover is manually manipulated by the user to move the needle cover from the retracted position, wherein the needle is exposed for injection or aspiration in the case of reconstitution or vein test, to the extended position, wherein the needle is enclosed. Such manual shield systems typically include some means to prevent the shield from being inadvertently moved to the extended position and prevent the shield from retracting following shielding of the syringe needle cannula, such as detents, interlocking ribs, threads, spiral grooves and the like. The principal disadvantages of manual syringe shield systems are that there is no positive assurance that the user will properly shield the needle cannula following use or that the needle cover is properly locked in the shielded position. In addition, some designs can allow inadvertent activation of the shield.
A second type of shield systems for syringes may be characterized as active shield systems. Active shield systems will typically include an energizer, such as a spring, which biases the shield or needle cover toward the extended position. Generally, the shield is initially retained in the retracted position by ribs, detents or the like and actuated by some action by the user. The principal advantage of active syringe shield systems is that, upon activation by the user, the shield or needle cover will move to enclose the needle cannula and lock the shield. Such active shield systems are generally activated by a button, movement of a component following injection or other release mechanism. That is, the user can generally activate the shield following injection to avoid contact of the shield with the patient""s skin prior to disposal. The principal problem with active shield systems for syringes is that again there is generally no positive assurance that the end user will properly shield the needle cannula of the syringe. Further, the shield may be inadvertently or prematurely activated prior to use as discussed further below. The shield may also be inadvertently or prematurely activated particularly during bulk shipping and processing.
The third type of shield systems may be characterized as passive shield systems. Passive shield systems also include an energizer, such as a spring, biasing the shield or needle cover toward the extended position as described above in regard to the active shield systems. However, the shield system is activated automatically generally upon completion of the injection. The primary disadvantages of the passive shield systems proposed by the prior art are that the user cannot select the timing of the actuation of the shield system and the shield or needle cover may be inadvertently or prematurely activated prior to use or completion of the delivery of the fluid in the syringe. That is, the shield can be activated while the needle cannula remains in the patient or the shield may be prematurely activated, particularly during normal manufacturing and assembly procedures and shipping. Shield systems are generally manufactured and assembled by the manufacturer of the shield system. The shield systems are then transported in bulk to a pharmaceutical company and must be handled using automatic feeding equipment, including feed bowls, etc., possibly resulting in inadvertent or premature activation of the shield.
The prior art also includes passive safety shield systems for syringes, wherein the shield system is actuated upon release of the plunger rod resulting in retraction of the syringe into the shield. However, in such shield systems, the syringe is withdrawn into the shield as the plunger rod is released, requiring the user to maintain the plunger against the force of the spring and requiring complete release of the plunger to shield the needle cannula of the syringe. In addition, the shield may contact the patient""s skin.
As described below, the passive shield system of this invention reduces the likelihood of premature activation of the shield and permits the end user to select the timing of the activation of the shield. That is, the user can activate or authorize the activation of the shield after removing the needle cannula from the patient, thereby reducing the risk of hitting the patient""s skin with the shield or needle cover. Further, the shield or needle cover moves axially relative to the syringe to enclose the needle cannula and lock the shield in the extended position following actuation, requiring only release of the plunger thumb pad.
As set forth above, the safety shield system of this invention is passive, but avoids the problems associated with the prior art passive shield systems. The shield system of this invention may be utilized with prefilled syringes of the type described above, but may also be used with other types of injection devices. Premature or inadvertent actuation of the shield system is minimized by an interlock system which allows packing, transportation in bulk and high speed feeding systems in bowls, etc. Further, the needle cover or shield is moved to enclose the needle cannula by release of the plunger, thereby giving the user the option of releasing the needle cover only after complete delivery of the fluid in the syringe and removal of the needle cannula from the patient, while assuring shielding of the syringe needle cannula prior to disposal.
The disclosed embodiment of the passive shield system of this invention includes four components, namely a generally tubular body having an open proximal end for receipt of a syringe, a generally tubular shield or needle cover telescopically supported by the body and extendable from a retracted position, wherein the syringe needle cannula is exposed, to an extended position enclosing the needle, a spring biasing the shield toward the extended position, and an annular or ring shaped member which interlocks with the body to prevent premature actuation of the shield or needle cover and which actuates the shield upon release of the plunger following complete delivery of the substance in the syringe. In the disclosed embodiment of the shield system of this invention, the needle cover or shield is telescopically received within the body and moveable axially to shield the needle cannula of the syringe as described. The spring and the ring shaped member are received in the open proximal end of the body such that the spring is biased between the ring shaped member and the shield. Prior to receipt of the syringe, the ring shaped member serves as a locking member preventing premature actuation of the shield. The ring shaped member or locking member includes a leg which forms a mechanical interlock with the body. In the disclosed embodiment, the ring shaped member includes two opposed axially extending legs which, in the preferred embodiment, extend proximally, preferably beyond the open end of the body, for actuation of the shield as described below. In the disclosed embodiment, the legs include opposed V-shaped locking surfaces which form a mechanical interlock with an opposed surface of the body adjacent the open proximal end preventing inadvertent or premature actuation of the shield during bulk shipping and processing as described above. In one disclosed embodiment, the projecting legs of the ring shaped locking member are partially enclosed or surrounded by walls which minimize inadvertent release of the shield by the user. Upon loading of a syringe in the open proximal open end of the shield system, the syringe flange engages the proximal end of the ring shaped member, driving the ring shaped member distally and the legs of the ring shaped member releasing the interlock between the ring shaped member or locking member and the body for actuation of the shield as now described.
In the preferred embodiment of the shield system of this invention, the tubular needle cover or shield includes at least two fingers which extend axially from the proximal end of the needle cover, each having a radial portion which is received on an opposed radial portion or ledge of the generally tubular body and releasably supports the needle cover or shield on the body. The radial portions on the fingers are operatively spaced relatively axially, such that the fingers function independently during actuation of the shield as described below. However, the radial surfaces or ledges on the body may alternatively be spaced axially and the radial portions of the fingers are then spaced axially only if required. One of the fingers is angled or bowed toward the radial support surface of the body, such that the angled or bowed finger is initially supported on the body prior to actuation of the shield. In the disclosed embodiment, the shield includes four fingers, wherein two opposed pairs of fingers are angled or bowed toward the radial support surfaces of the body and the other pair of fingers extend generally axially or are bowed away from the body, providing balanced support for the shield.
Upon receipt of the syringe in the open proximal end of the shield system, the interlock between the body and the ring shaped member is released and the ring shaped member is free to move axially in the body against the force of the spring. The annular or ring shaped member includes a first distal camming surface opposite the finger. In the disclosed embodiment, the shield includes two pairs of fingers opposite the outwardly angled or bowed fingers being referred to hereinafter as the first pair of fingers. When the tubular shield or needle cover is telescopically received within the body, as described above, the first pair of fingers bowed or angled outwardly and the radial portions are spaced distally from the radial portions of the fingers which extend generally axially or are angled inwardly, which are referred to hereinafter as the second pair of fingers. The first pair of fingers therefore initially retains the shield in a first retracted position. The ring shaped member also includes a second camming or biasing surface or surfaces opposite the second pair of fingers of the needle cover.
The shield is thus actuated in stages, as follows. First, as the injection is made, the thumb pad of the plunger assembly of the syringe engages the proximally extending legs of the ring shaped member, driving the ring shaped member distally in the body. The first camming surfaces of the ring shaped member opposite the first pair of fingers then releases the first pair of fingers and the shield moves axially to a second retracted position because the second biasing or camming surfaces of the ring shaped member opposite the second pair of fingers simultaneously biases the second pair of fingers radially outwardly to receive the radial surfaces on the opposed radial surfaces or ledges of the body, releasably retaining the shield in a second retracted position. In the preferred embodiment, the second retracted position is close to or adjacent the first retracted position of the shield. Then, upon completion of the injection and release of the plunger by the user, the spring biases the ring shaped member proximally, releasing the second pair of fingers, and the shield is then driven distally to shield the needle as described. In the preferred embodiment, the body further includes opposed detents adjacent the distal end of the body which receive a radial portion or annular rib of the shield adjacent its proximal end which prevents retraction of the shield following actuation. The shield system of this invention is thus passive in the sense that an additional action by the user is not required to activate the shield. That is, the shield is automatically activated upon release of the plunger. However, the user can also select the timing of the actuation of the shield, for example, by releasing the plunger after removal of the needle cannula from the patient, thereby eliminating engagement of the needle shield against the skin of the patient. Further, upon release of the syringe plunger by the user, the spring drives the shield from its second retracted position to its extended position, enclosing the syringe needle cannula, rather than retracting the syringe into the shield as disclosed in the prior art. Another advantage of the shield system of this invention is that it may be used with conventional syringes without requiring special plungers, thumb pads, etc. A further advantage is that the shield system of this invention may be designed for different sizes of syringes.
As set forth above, the syringe is received in the open proximal end of the shield system. In the disclosed embodiments, the syringe is retained in the body by opposed abutment surfaces adjacent the open proximal end of the body which receive the flange of the syringe therebetween. In one disclosed embodiment, the open proximal end of the body includes inwardly inclined camming surfaces which are engaged by the flange of the syringe. The camming surfaces bias the retainer elements to retain the syringe flange between the opposed abutment surfaces. The proximal end of the body also includes lateral slots defining the opposed distal abutment surfaces. Finally, the proximal end of the body includes axial slots which receive the legs of the ring shaped or locking member.
In another preferred embodiment, the proximal end of the body is generally planar and the body includes generally hook-shaped retainer elements. The abutment surfaces which retain the syringe flange comprise the generally planar open proximal end of the body and the overlying hook-shaped elements. This embodiment includes two pair of spaced ribs on opposed sides of the body which receive the legs of the locking member therebetween each having an inwardly facing proximal hook-shaped end portion which receives and retains the syringe flange and an outwardly facing proximal hook-shaped end portion which receives the locking portion of the ring shaped member. In this disclosed embodiment, the opposed sides of the proximal open end of the body also includes opposed abutment surfaces supported on posts extending from the planar open end of the body which also receive the syringe flange. In this embodiment, the syringe flange is substantially exposed permitting visual inspection of the securement of the syringe in the body.
Other advantages and meritorious features of the shield system of this invention will be more fully understood from the following detailed description of the preferred embodiments, the appended claims and the drawings, a brief description of which follows. As will be understood, the terms proximally and distally are used herein for descriptive purposes only and the term proximally refers to the components or portions of a component closest to the hand of the user, such as a healthcare worker or patient, and the term distally refers to the component or a portion of a component furthest from the hand of the user. Further, the preferred embodiments of the shield system for syringes described below are intended to be exemplary only and do not limit the invention except as set forth in the appended claims.